1. Field of the Invention
The invention generally relates to microprogrammed data processing systems and in particular to apparatus for generating and storing an effective digit count of a resultant operand during the processing of a decimal numeric instruction.
1. Description of the Prior Art
Data processing systems process data stored in memory in the form of an operand consisting of decimal digits. The length of the field in memory assigned to storing a particular operand contains as many memory locations as is required to store the largest possible number of decimal digits for that operand.
In many cases the operand stored in that field would require fewer decimal digits than does the maximum. When the operand is the result of the system processing a decimal numeric instruction it is necessary to determine the number of effective digits in the resultant operand.
The Honeywell 6000 uses leading zero count logic at all times and when the effective digit count is needed for storing the resulting operand, the leading zero count is subtracted from 64 decimal digits which is the maximum operand size.
The approach takes a number of machine cycles and requires a relatively large amount of hardware. This reduces the throughput of the system at an increased cost.